Universal Serial Bus (USB) is an example of an interface “Standard” that defines the cables, connectors and communications protocols used in a bus for connection, communication and power supply between a “host” electronic device (such as a personal computer) or “hub” and various peripheral electronic devices such as keyboards, pointing devices, digital cameras, printers, portable media players, disk drives, network adapters, smartphones, and video game consoles.
Conventional USB interfaces uses electrical connectors and cables (with electrical wires) to interface from the host (alternatively a hub) device to peripheral devices. The connectors are mechanical in nature, and may wear down and eventually fail after repeated use. The existing mechanical connectors, which may be physically different for the host and peripheral devices, use electrical signaling contacts to communicate (transfer, transport data signals) from one device to another. These connectors must engage one another completely in order to ensure a good connection. The electrical signaling is also not ideal as it has many discontinuities in the wiring through the connector and wiring associated with the cable. This imposes an inherent limit on the speed of USB and increases the power budget for successfully transmitting signal over a significant distance. The length of a USB cable is practically limited (by cable delays, etc.) to approximately 5 meters. Power may be supplied via the USB connectors and cables to “bus-powered” peripheral devices. Current draw from the bus is normally limited to 100 mA or 500 mA.
Bluetooth is a wireless technology that allows a user to connect two Bluetooth-enabled devices, in a wireless process known as pairing, that eliminates the need for cabled connections between devices. Bluetooth can also be used to set up a wireless personal area network (WPAN). A USB-to-Bluetooth adapter inserts (plugs) into a USB port of a host device (such as a computer) which is not Bluetooth-enabled to provide Bluetooth functionality for the device.
Bluetooth headsets are known, and generally have electronics (circuitry, such as transceivers) for Bluetooth functionality (communicating wirelessly with Bluetooth-enabled host devices) in addition to conventional audio transducers (e.g., speaker, microphone). Bluetooth headsets cost much more than conventional headsets, and may thus be prohibitively expensive to ship with portable devices. Batteries are needed to operate the electronics, and this creates a larger form factor for the headsets as well as higher costs for both the manufacturer and the end user.
Bluetooth audio adapters are also known, which can be used with conventional headsets. The headset is plugged into the adapter, which communicates wirelessly with the Bluetooth-enabled host device. These adapters require power to operate, typically from internal batteries, which adds to their cost and weight. And, when the batteries are drained, the adapter no longer functions.
A signal is a physical quantity which varies with respect to time, space & contain information from source to destination. Electrical signals representative of audio data are discussed herein, and may be in analog or digital format. A digital-to-analog converter (DAC) is an electronic device that converts a digital signal to an analog signal. Conversely an analog-to-digital converter (ADC) is an electronic device that converts an analog signal to a digital signal. Electromagnetic (EM) signals are discussed herein, and may comprise a radio frequency (RF) carrier which may be modulated by an electrical signal provided to a transmitter (Tx), and conversely demodulated by a receiver (Rx) to generate an electrical signal. Typically, electromagnetic signals which are in the EHF (extremely high frequency) range of frequencies, such as from 30 to 300 gigahertz, or higher may be discussed herein.
I2S, also known as Inter-IC Sound, Integrated Interchip Sound, or IIS, is an example of a serial bus interface Standard (digital audio serial protocol) used for communicating digitized audio data between devices (or chips, or chips and devices). Typically, the bus comprises three (3) lines: a serial data line (SD) for two time-multiplexed data channels, a word select line (WS) and a continuous serial clock line (SCK).